在突破更高的記錄密度過程當中，降低記錄雜訊與提高熱穩定性為必須克服的兩大重點。提升傳統水平式記錄媒體的訊號雜訊比SNR的方法包括一、增加每個記錄元內的晶粒數(N1/2)，即增加訊號強度，二、降低Mrt，即降低雜訊強度。兩種方法都朝降低磁能障KuV的方向努力，但將會劣化熱穩定性，即本身磁能無法克服熱能的擾動而造成磁矩反轉。全新設計的 AFC媒體利用雙層鐵磁性層耦合的效果，擁有較大的磁矩翻轉體積而克服超順磁的極限，且具有低Mrt、高矯頑場的特色而降低了記錄雜訊，成為新一代的記錄媒體。
在本實驗中，除了調整間隔層Ru的厚度以得到AFC結構的最大交換場，更進一步討論界面耦合強度對磁性質表現的重要性，藉由引入純Co或調整成分來加強耦合強度以利穩定層的反轉，但結果卻發現，此種方法在增強交換場的同時可能伴隨著劣化主記錄層的矯頑場或延緩穩定層反轉時間的反效果。有基於此，以新的雙穩定層結構不但可維持強的界面耦合力，亦可抑制穩定層矯頑場的增加而使其更易於反轉，主記錄層的矯頑場也不至於因結構的改變而降低。

Lower noise and higher thermal stability are two main key points in the process of achieving high areal density recording. The method of promoting SNR includes increasing the number of grain per bit to increase intensity of signal and decreasing Mrt to decrease noise. Both two methods improved SNR in the opinion of reducing energy barrier KuV and would reduced the ability to resist agitation from thermal energy and leaved the moments unstable. Antiferromagnetically coupled media was proposed in 1999 as a pathway for extending high-density longitudinal recording media while maintaining thermal stability. The important advantages of AFC media are: high signal resolution due to smaller Mrt and higher thermal stability due to larger grain volume.
I have investigated that the interlayer exchange coupling constant J and exchange field are enhanced by conventional AFC media with Co interlayer on each side of Ru. But the Hc of upper layers decreases and Hc of lower layers increases with tCo, which is opposite to the useful properties of AFC media. To prevent the increase of Hc,LL due to inserting Co layer, I develop another different design of advanced AFC media structure. In the new structure, I retain the interlayer Co on the bottom side of Ru and insert a nonmagnetic layer such as Ru or CoCr with low content of Co into the interface of LL/Co to isolate interaction between Co interlayer and lower layer. Advantages of inserting NM layer into double stabilizing layers are as follows：higher interlayer exchange coupling, easier switching of lower layers, and lower net Mrt.

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